The exemplary embodiment relates to the digital imaging arts. It finds particular application in connection with a user interface for a duplex printing system which facilitates registration of images on one or both sides of a printed sheet. However, it is to be appreciated that the exemplary user interface may have other applications.
In digital printing systems, such as laser printers, copiers, and multifunction devices, documents are frequently printed in a duplex (two sided) printing process. Typically, in a duplex process, an image is printed on a first side of a sheet of print media by applying colorants, such as toners, to the sheet. Heat and pressure are then applied, in a process known as fusing, to fix the image permanently to the sheet. Thereafter, an image is formed on the second side of the sheet and fused. Printing systems typically include controls for adjusting registration and skew for a particular print engine, to ensure that images are properly aligned on the page. However, these controls do not account for differences between one side of the sheet and the other. During the fusing of the image to the first side of the sheet, the sheet typically shrinks. As a result, the images on the front and back sides of the sheet may have different magnifications.
For a translucent print medium, such as paper, such a lack of page to page consistency is noticeable to the customer and may be perceived as a printing defect. For-example, a page number printed on the bottom-center position of the first side of a two-sided, printed document should align exactly with the page number printed on the reverse side. Additionally, when the printing system is used for overprinting, in which one image is superimposed on another, the shrinkage can lead to misregistration of the images on one side of the sheet. When the overprinting is used for adding content to a preprinted form, one side of the sheet may be correctly registered, while for the other side, there may be misregistration of the printed image with the structure of the form. When this occurs, considerable time and materials may be wasted in the course of reloading and raster image processing (ripping) of the print job in order to try to mitigate the problem. While some geometric adjustment functions exist in the video path software routines, they do not allow rapid adjustments to be made to these parameters. Print engines have hardware for making mechanical adjustments to magnification, registration, and skew, but the hardware does not compensate for fuser shrinkage, paper cut tolerances, and pre-print image characteristics, which are independent of the print engine setup itself.